The center has five main areas of study: 1. Heritable disorders of connective tissue, including the osseous skeleton. Clinical delineation and characterization, search for the basic defect, and management are aspects studies. 2. Abnormalities of collagen in heritable disorders of connective tissue. 3. Mapping the chromosomes of man. This is approached by family linkage studies of mendelian traits and chromosomal aberrations and by cell hybridization. 4. Dynamics of genes in populations, especially pathologic genes and especially among the Amish. 5. Theoretic and practical aspects of genetic counseling and record-keeping. 6. Detection and characterization of new rare and commom genetic variants.